diff options
author | Li Zefan | 2009-03-31 15:23:16 -0700 |
---|---|---|
committer | Linus Torvalds | 2009-04-01 08:59:13 -0700 |
commit | 610a77e04a8d9fe8764dc484e2182fa251ce1cc2 (patch) | |
tree | ec55b9b3698321c3e85cd649fa927554027c75d0 | |
parent | e2f17d9459aeccf4e013e31cbd741d6b1858eec4 (diff) |
memdup_user(): introduce
I notice there are many places doing copy_from_user() which follows
kmalloc():
dst = kmalloc(len, GFP_KERNEL);
if (!dst)
return -ENOMEM;
if (copy_from_user(dst, src, len)) {
kfree(dst);
return -EFAULT
}
memdup_user() is a wrapper of the above code. With this new function, we
don't have to write 'len' twice, which can lead to typos/mistakes. It
also produces smaller code and kernel text.
A quick grep shows 250+ places where memdup_user() *may* be used. I'll
prepare a patchset to do this conversion.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Americo Wang <xiyou.wangcong@gmail.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | include/linux/string.h | 1 | ||||
-rw-r--r-- | mm/util.c | 30 |
2 files changed, 31 insertions, 0 deletions
diff --git a/include/linux/string.h b/include/linux/string.h index d18fc198aa2f..8852739f36df 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -12,6 +12,7 @@ #include <linux/stddef.h> /* for NULL */ extern char *strndup_user(const char __user *, long); +extern void *memdup_user(const void __user *, size_t); /* * Include machine specific inline routines diff --git a/mm/util.c b/mm/util.c index 37eaccdf3054..7c122e49f769 100644 --- a/mm/util.c +++ b/mm/util.c @@ -70,6 +70,36 @@ void *kmemdup(const void *src, size_t len, gfp_t gfp) EXPORT_SYMBOL(kmemdup); /** + * memdup_user - duplicate memory region from user space + * + * @src: source address in user space + * @len: number of bytes to copy + * + * Returns an ERR_PTR() on failure. + */ +void *memdup_user(const void __user *src, size_t len) +{ + void *p; + + /* + * Always use GFP_KERNEL, since copy_from_user() can sleep and + * cause pagefault, which makes it pointless to use GFP_NOFS + * or GFP_ATOMIC. + */ + p = kmalloc_track_caller(len, GFP_KERNEL); + if (!p) + return ERR_PTR(-ENOMEM); + + if (copy_from_user(p, src, len)) { + kfree(p); + return ERR_PTR(-EFAULT); + } + + return p; +} +EXPORT_SYMBOL(memdup_user); + +/** * __krealloc - like krealloc() but don't free @p. * @p: object to reallocate memory for. * @new_size: how many bytes of memory are required. |